Depends what you mean by "best" of course! If you want what I would call the best in terms of readability, Rick Atkinson's "Liberation Trilogy" is an absolutely fantastic work for a history of the US in the war against Germany, geared towards a general audience. It doesn't focus exclusively on the period you're asking, but book III, "The Guns at Last Light: The War in Western Europe, 1944-1945", does of course cover it. To be sure, it is a popular history, not an academic one. Atkinson is a journalist by profession, but he is - in my opinion - one of the best 'journalists doing history' out there, and reviews generally would agree - I, II, III

Now, if you literally just want a ton of information thrown at you (and are on a budget), the so called "Greek Books", the US Army's official history of the war, are free online, and three volumes - "BREAKOUT AND PURSUIT", "THE LORRAINE CAMPAIGN", and "THE SIEGFRIED LINE CAMPAIGN" - cover this span of time, each one with a pretty hefty amount of depth (600+ pages per volume often). It isn't heavy on academic analysis, or the social side of war, mostly just nuts and bolts of tactics, strategy, and logistics, but hard pressed to think of anything that dives deeper into that.